Use MongoDB db.collection.remove(query) in java

Question

Is there a way in the MongoDB Java driver to call the db.collection.remove(query) method that I see in the MongoDB shell documentation? That is, I know the exact criteria that I need to find all the documents I want to delete from MongoDB, but I can't find a way to make one call to remove those records in one trip. All that I can figure out is to find the documents and then delete them one by one.

I see this http://docs.mongodb.org/manual/reference/method/db.collection.remove/ which implies there should be a way to do it, but I can't figure out the Java calls to get me that to that call.

Thank you for your help

Answer 1

To remove documents with an age property of 25.

MongoClient mongo = new MongoClient(new ServerAddress("localhost", 27017));
DB db = mongo.getDB("thedb");
DBCollection collection = db.getCollection("test");

BasicDBObject query = new BasicDBObject();
query.append("age", 25);

collection.remove(query);

DBCollection and BasicDBObject are two of the most important classes in the Java API.

Answer 2

Also to remove specific values from you document you can use following code with Mongo Java 3.2

Document docToDelete = new Document("Designation", "SE-1");
objDbCollection.findOneAndUpdate(new Document("Company", "StackOverflow"), new Document("$unset", docToDelete));

Above code will first find document having company = StackOverflow and then unset (remove) Designation = SE-1 key/value from that document.

Answer 3

Add and Update Mongo

public class App {
public static void main(String[] args) {

  try {

Mongo mongo = new Mongo("localhost", 27017);
DB db = mongo.getDB("yourdb");

// get a single collection
DBCollection collection = db.getCollection("dummyColl");

//insert number 1 to 10 for testing
for (int i=1; i <= 10; i++) {
    collection.insert(new BasicDBObject().append("number", i));
}

//remove number = 1
DBObject doc = collection.findOne(); //get first document
collection.remove(doc);

//remove number = 2
BasicDBObject document = new BasicDBObject();
document.put("number", 2);
collection.remove(document);

//remove number = 3
collection.remove(new BasicDBObject().append("number", 3));

//remove number > 9 , means delete number = 10
BasicDBObject query = new BasicDBObject();
query.put("number", new BasicDBObject("$gt", 9));
collection.remove(query);

//remove number = 4 and 5
BasicDBObject query2 = new BasicDBObject();
List<Integer> list = new ArrayList<Integer>();
list.add(4);
list.add(5);
query2.put("number", new BasicDBObject("$in", list));
collection.remove(query2);

//print out the document
DBCursor cursor = collection.find();
    while(cursor.hasNext()) {
         System.out.println(cursor.next());
    }

    collection.drop();

    System.out.println("Done");

  } catch (UnknownHostException e) {
e.printStackTrace();
  } catch (MongoException e) {
e.printStackTrace();
  }